Diagnostic performance of conventional MRI using T1W and T2W for primary lymph node staging in intermediate- and high-risk prostate cancer patients prior to pelvic lymph node dissection.

PURPOSE: To assess the accuracy of conventional MRI with T1- and T2-weighted sequences in detecting lymphatic nodal spread (N1) in intermediate- and high-risk prostate cancer (PCa) patients via morphological criteria alone, extended pelvic lymph node dissection (ePLND) was used as the reference standard.

METHODS

This prospective observational study included patients between 2009 and 2016 with intermediate- and high-risk PCa according to the D'Amico criteria and an estimated risk of N1 > 20% on the basis of the Briganti nomogram. All patients underwent MRI prior to ePLND. Interobserver analysis was conducted across three centers.

RESULTS

Ninety-nine men, mean age 67 (5.7 SD), 93% high-risk PCa patients and 39.4% with N1 disease, according to ePLND, were evaluated. The pooled sensitivity of MRI for detecting N1 was 24.6% (95% CI: 16.3-35.1), whereas the pooled specificity was 95% (95% CI: 85.3-98.8). Interobserver agreement was moderate (Fleiss' κ = 0.56). All readers failed to identify patients with high-volume N1, and the identification of those with a high number of N1 events was inconsistent across readers. The strengths of this study include the high number of N1 cases, with a median of 17 (6-40) harvested lymph nodes per participant. Limitations include the time interval between MRI and ePLND (median of 44 days) and the lack of standardized lymph node evaluation criteria, reflecting real-world clinical practice.

CONCLUSION

MRI using only T1W and T2W sequences has demonstrated limited effectiveness in lymph node staging for intermediate- and high-risk prostate cancer, even in high-volume metastatic disease. Additionally, interobserver analysis shows only moderate agreement.